Automatic sprinkler



Jan. 16, 1934.

W. K. HODGMAN, JR

AUTOMATIC SPRINKLER Filed Sept. 16, 1932 Ammo 1 I F \nvenTor. \/\/i|\isKHodgmcn \Jr.

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. Patented Jan. 16, 1934 PATENT," OFFICE AUTOMATIC SPRINKLER Willis K.Hodgman, Jr., Taunton, Mass.

Application September 16, 1932 Serial No. 633,488

12 Claims.

This invention relates to a frangible vessel and more particularly to anautomatic sprinkler employing such a frangible vessel as a strut ormeans for normally holding the sprinkler closed.

In this type of device the vessel usually made of glass or similarmaterial contains an expansible fluid designed, when the temperaturesurrounding the'vessel reaches a predetermined degree, to expand andburst the vessel, thus destroying its function as a strut and effectingthe opening of the sprinkler head. This type of device is highlydesirable wherever the conditions are such as to interfere with theaccuracy and eificiency of operation of the usual type of sprinkler heademploying fusible metal struts or operating members held together or inposition by fusible metal. The type of sprinkler head operating memberto which this invention relates is not subject to corrosive action ofgases, fumes, or other impurities frequently existing in manufacturingplants or other places where sprinkler systems are installed.

In this type of sprinkler head it is obvious that the expansible fluidmust be maintained indefinitely unchanged both in amount and in quality,otherwise the accuracy of operation of the sprinkler head would beimpaired. This result has heretofore been solved by sealing by fusionthe glass vessel containing the expansible fluid. But fusion requiresthe application of a high temperature which prevents the annealing ofthe glass, sets up internal strains in the glass, or requires the vesselto be made of highly specialized material. Furthermore, the heat offusion has its effect upon the expansible fluid itself, thus requiringextremely careful manipulation and designing of the vessel.

The present invention has for its object to provide a frangible vesselof non-corrosive material, preferably glass, in which the open end ofthe vessel is closed and tightly sealed by a'st0pper,'

also of non-corrosive material and preferably of the same material asthe vessel.

The object of the invention is further to provide such a construction inwhich the stopper is held seated on the open end of the vessel with thejoint between the two transmitting substantially the entire pressure,exerted longitudinally of the vessel and stopper, in a direction normalto the joint. Consequently the heavy pressure, such as required in asprinkler strut, presents no deleterious resultants acting to splitapart or to contract the walls of the vessel. I

Theobject of the invention is further to provide a frangible vessel ofthis type which may thus be filled with the expansible fluid, sealedwithout the use of heat, and installed in position as a sprinkler strutor for other purposes.

The object of the invention is further to provide such a device in whichthe frangible vessel may be made of a homogeneous material, such asannealed glass, having uniform characteristics throughout and notpossessing any deleterious internal strains. Thus uniformity inmanufacture is readily and economically attained. Thus also the requiredcharacteristic reactions of the vessel when bursting temperature hasbeen reached are uniform and reliable.

These and other objects and features of the invention will appear morefully from the accom-' panying description and drawing and will beparticularly pointed out in the claims.

In the drawing:

Fig. 1 is an elevation of a sprinkler head em- I bodying a preferredform of the invention;

Fig. 2 is a detail enlarged in vertical cross section of a portion ofthe construction shown in Fig. 1;

Fig. 3 is a detail partially broken away to illus- The invention is hereillustrated in a preferred form as applied to an automatic sprinklerhead. A sprinkler head of a familiar type is shown in which the base 1is threaded at 2 for attachment to the sprinkler system. This basepresents at its upper end a mouth or opening 3 through which the wateris discharged. From the base and rigid therewith rises an arch 4. Ascrew 5 is threaded into the arch in alignment with the mouth of thebase and upon this screw is mounted the usual deflector 6. The mouth ofthe base is closed by a cover 7, preferably made of metal, and a gasket8 of soft metal, such as copper, is preferably interposed between thecover 7, and the mouth of the base.

The strut, to which this invention particularly relates, is interposedbetween the screw 5 and the cover 7 and as usual acts normally to holdthe cover in place against the pressure of the water and thus preventany discharge of the water until the strut is removed.

The strut, as shown, comprises the vessel 9, the stopper 10, the cap 11and the spacer 12.

The vessel 9 is formed of frangible non-corrosive material and for thatpurpose homogeneous, annealed glass is preferable, such glass, forexample, as commonly employed for oven wear is efficient. The glassvessel 9 is formed into the required shape by any of the usualprocesses, such as molding or blowing and desirably presents arelatively thin walled globular body 13 and a relatively thick walledtubular neck 14 having a relatively small opening 15 therethrough. Theopen end of this bottle-shaped vessel is ground or finished off flat.The stopper 10 is also made of non-corrosive material and preferably ofthe same material as the vessel and is desirably of disk shape and inany event has its surface opposed to the end of the bottle neck alsofinished or ground flat so thatit may contact evenly and directly andtightly with the end of the bottle neck thus hermetically sealing thevessel.

The cap 11 which is made of rigid material and preferably of metal fitsover the stopper and presents an extended surface conforming to the topsurface of the stopper. This cap also presents a peripheral flange l6,surrounding, spaced from, and protecting the joint between the stopperand bottle neck end. The cap 11 directly engages the screw 5 and forthat purpose may be provided with a projection 17 seating in acorresponding recess in the end of the screw 5.

The lower end of the globular body 13 of the vessel is seated on thecover 7. When the vessel is formed by molding or so as to present ahighly accurate shape, it may seat directly in a recess in the cover '7.If, for any reason, the globular body is slightly irregular, the covermay have connected therewith or embodied therein a cradle of resilientmaterial as shown at 18 in Fig. 4 to receive and conform to and presentan even bearing seat for the base of the globular body.

The frangible vessel may be filled with any suitable fluid, which has alow freezing point and which will act to expand and burst the vessel atthe predetermined or required temperature. It may be entirely orpartially filled as required by inserting a measured quantity of thefluid. A simple way of filling the vessel is first to fill it with thefluid, then immerse the vessel in water with the open end above thelevel of the water, then raise the water to the temperature at which thesprinkler head is to operate and maintain it at this temperature untilthe fluid has ceased to overflow and the surface of the end of the neckof the vessel is dry. The bottle is then removed from the water andallowed to assume room temperature. The stopper is then placed inposition and the strut assembled. This leaves the neck of the bottlefilled with air as shown in Fig. 2. With this arrangement, when heat, asin the case of a fire, is applied to the sprinkler head, the fluidexpands until, at the bursting temperature, the air in the vessel ishighly compressed and immediately the expansion of the liquid bursts thevessel and the expanding air breaks it into fragments, shattering theglass and removing the strut entirely out of the way.

With the sprinkler head assembled as shown in Fig. 2, the screw 5 isturned down until the strut is under the requisite pressure to offsetthe pressure of the water in the system, together with a considerablefactor of safety, and prevent the water from issuing from the mouth 3when the strut is in place. When in this position, the screw 5 isusually fastened in place by the pin 19.

It will be seen in the preferred form of the invention illustrated thatthe pressure exerted longitudinally of the strut is transmitted throughthe rigid cap 11 to the stopper 10 and that with the spacer 12, which ispreferably of some resilient material such as a thin disk of lead,ensures the even distribution of this pressure. Thus the stopper isforced and held squarely and firmly against the end of the bottle neck.But as the opposed surfaces of the stopper and bottle neck are flat thepressure exerted is normal to the joint between the stopper and bottleneck throughout so that there are no deleterious resultants of thepressure acting either to split the bottle apart or to contract thewalls of the bottle, that is, the action is entirely different from thatin the case, for example, of a glass stoppered medicine bottle where thestopper is forced into the mouth. of a bottle, or as in the case of acap forced over the outside of a bottle. Not only does the transmittedpressure act as set forth, but it actswith all its force to hold thestopper and bottle neck end tightly seated together and thus prevent anypossible escape of the contents of the vessel.

As afurther protection tothe joint, the surface of the bottle neck orthe opposed surface of the stopper, or both, may be coated with asuitable filmy coating, shown greatly exaggerated at 20 in Fig. 2, suchas sodium silicate which, in the case of glass, is peculiarly suitable.Such a coating acts to form a precautionary sealing gasket.

As a still further protection to the joint, particularly to guard itagainst the action of moisture or other foreign matter in theatmosphere, the space between the peripheral flange 16 of the cap 11 andthe vessel may be packed with filling material 21 as illustrated in Fig.3. An asphaltic mixture, for example, may be used for this purpose.

It will thus be seen that the device is one of extreme simplicity. Itmay be readily and easily constructed. Uniformity of conditions isreadily obtained. The filling of the vessel with the predeterminedamount of the expansible fluid is a simple matter. The assembling of thestrut is also simple. No injurious and incalculable internal strains areset up in the vessel such as result from fusion. While the strut iscapable of withstanding high pressure, far above that required to holdthe sprinkler closed, there are no resultants from this pressure actingto split apart or contract the walls of the vessel and the pressureitself acts to ensure a tight joint between the stopper and vessel. Theentire device, therefore, is unaffected by corrosive action, is highlydependable, is accurate in operation and endures indefinitely withoutchange.

Having thus described the invention, What is claimed as new, and desiredto be secured by Letters Patent, is:

1. A frangible vessel of non-corrosive material havingan open end andcontaining a predetermined amount of an expansible fluid; a stopper ofnon-corrosive material seated on, and tightly closing, the open endthereof; the joint between the vessel and the stopper transmittingsubstantially the entire pressure, exerted longitudinally of the vesseland stopper, in a direction normal to the joint thus to avoiddeleterious resultants acting to split apart or to contract the walls ofthe vessel; the said fluidacting, when the stopper and vessel are thusheld tightly closed by the said longitudinally exerted pressure and thetemperature of the fluid has been raised to a predetermined degree, toexpand, burst and scatter the vessel.

2. A homogeneous annealed glass vessel having an open end containing apredetermined amount of an expansible fluid; a glass stopper; saidstopper and the open end of the vessel presenting flat ground opposedsurfaces with the stopper seated on, and tightly closing, the open end;the joint between the vessel and the stopper transmitting substantiallythe entire pressure, exerted longitudinally of the vessel and stopper,in a direction normal to the joint thus to avoid deleterious resultantsacting to split apart or to contract the walls of the vessel; the saidfluid acting, when the stopper and vessel are thus held tightly closedby the said longitudinally exerted pressure and the temperature of thefluid has been raised to a predetermined degree, to expand, burst andscatter the vessel.

3. A homogeneous annealed glass vessel .and stopper having theconstruction defined in claim 2, together with a filmy coating betweenthe stopper and the open end of the vessel forming a precautionarysealing gasket.

4. A homogeneous annealed glass vessel and stopper having theconstruction defined in claim 2, together with a coating of sodiumsilicate between the stopper and the open end of the vessel forming aprecautionary sealing gasket.

5. A sprinkler head comprising a base having a discharge mouth; an armextending from the base to a point opposite the mouth; a strut mountedbetween the arm and the mouth to maintain the mouth normally closedcomprising a homogeneous annealed glass bottle having a relatively thinwalled globular body and a relatively thick walled tubular neck with asingle flat ground open end, a glass stopper having a fiat groundsurface seating on the bottle neck end, and a cap engaging an extendedsurface of the stopper opposite the ground surface and acting todistribute evenly to the stopper and thence to the bottle, in adirection normal to the ground surface and end, pressure exerted on thecap longitudinally of the bottle between the arm and mouth; and apredetermined amount of a substance within the bottle acting, when thesurrounding temperature has been raised to a predetermined degree, toexpand and burst and scatter the bottle.

6. A sprinkler head comprising the construction defined in claim 5,together with a coating of sodium silicate between the stopper andbottle neck end forming a precautionary sealing gasket.

'7. A sprinkler head comprising the construction defined in claim 5,together with a resilient spacer between the engaging surfaces of thecap and stopper acting to distribute the pressure evenly to the stopper.

8. A sprinkler head comprising the construction defined in claim 5,together with a soft metal cushion between the engaging surfaces of thecap and stopper acting to distribute the pressure evenly to the stopper.

9. A sprinkler head comprising a base having a discharge mouth; an armextending from the base to a point opposite the mouth; a strut mountedbetween the arm and the mouth to maintain the mouth normally closedcomprising a homogeneous annealed glass bottle having a relatively thinwalled globular body and a relatively thick walled tubular neck with aflat ground end, a stopper having a fiat surface hermetically sealingthe bottle neck end, and a cap engaging an extended surface of thestopper opposite the ground surface and acting to distribute evenly tothe stopper and thence to the bottle, in a direction normal to theground surface and end, pressure exerted on the cap longitudinally ofthe bottle between the arm and mouth, the said cap having a peripheralflange surrounding, spaced from, and protecting the joint between thestopper and bottle neck end; and a predetermined amount of a substancewithin the bottle acting, when the surrounding temperature has beenraised to a predetermined degree, to expand and burst and scatter thebottle.

10. A sprinkler head comprising the construction defined in claim 9together with filling material in the space between the cap and the saidjoint acting to exclude moisture or other foreign matter in theatmosphere from the joint.

11. A sprinkler head having a base with a mouth for the discharge ofwater and an opposed arch; cover for the mouth and a strut between thecover and the arch; the said strut comprising a homogeneous annealedglass bottle having a relatively thin walled globular body and arelatively thick walled tubular neck with a fiat ground end; a glassstopper having a flat ground surface seating on the bottle neck end; acap engaging an extended surface of the stopper opposite the groundsurface and acting to distribute evenly to the stopper and thence to thebottle, in a direction normal to the ground surface and end, pressureexerted on the cap longitudinally of the bottle; the cover having a seatto receive, and conform to the base of, the globular body of the bottle;and a liquid within the bottle having a low freezing point and exerting,when raised to the predetermined operating temperature of the sprinklerhead, an expansive force suflicient to burst the glass bottle of thestrut and remove it from between the mouth and arch of the base.

12. A releasing device having opposed abutments; a strut between saidabutments comprising a frangible vessel of non-corrosive material havingan opening presenting a flat end surface and containing a predeterminedamount of an expansible fluid, a stopper of non-corrosive materialpresenting a flat surface fitting against the fiat end surface of thevessel and hermetically closing the vessel; the said fluid acting whenthe stopper and vessel are held tightly closed by pressure exertedbetween said abutments longitudinally of the vessel and stopper and thepressure of the fluid has been raised to a predeteri" mined degree, toexpand, burst and scatter the vessel.

WILLIS K. HODGMAN, JR.

